Curro N J, Slichter C P
Department of Physics and Materials Research Laboratory, University of Illinois, Urbana 61801, USA.
J Magn Reson. 1998 Feb;130(2):186-94. doi: 10.1006/jmre.1997.1295.
Measurement of T2G, the Gaussian component of the spin-echo envelope of planar Cu nuclei in high-temperature superconductors, gives important information about the real part of the Cu electron spin susceptibility. In the traditional picture of the planar Cu echo decay, the internuclear coupling is assumed to remain static with respect to spin-lattice relaxation and mutual exchange fluctuations. In some circumstances, however, this assumption breaks down. We calculate the internuclear corrections arising from spin-lattice relaxation to the conventional theory of T2G and show that T2G can be easily corrected for these effects. We argue that mutual exchanges due to the perpendicular indirect couplings are suppressed in these materials. For YBa2Cu4O8, we find a correction on the order of 10% in T2g and using the corrected values we find that the isotope ration 63T2G/65T2G agrees with theory.
对高温超导体中平面铜核自旋回波包络的高斯分量T2G进行测量，可得到有关铜电子自旋磁化率实部的重要信息。在平面铜回波衰减的传统图像中，假设核间耦合相对于自旋 - 晶格弛豫和相互交换涨落保持静态。然而，在某些情况下，这一假设不成立。我们计算了自旋 - 晶格弛豫对传统T2G理论产生的核间修正，并表明可以很容易地针对这些效应校正T2G。我们认为，在这些材料中，由垂直间接耦合引起的相互交换受到抑制。对于YBa2Cu4O8，我们发现T2g的校正幅度约为10%，使用校正后的值，我们发现同位素比率63T2G/65T2G与理论相符。
